"Dudu'nun karnı"  is  a POSSESSIVE CONSTRUCTION Karın = Tummy / Abdomen Dudu'nun karnı = Tummy of Dudu / Dudu's tummy Benim karnım = My tummy Senin karnın = Your tummy Onun karnı = His/Her/Its tummy  ->  Ahmet'in karnı / Leyla'nın karnı / Dudu'nun karnı Bizim karnımız = Our tummy / tummies Sizin karnınız = Your tummy / tummies Onların karnı = Their tummy / tummies Explanation in English: http://www.turkishlanguage.co.uk/possessiveforms.htm https://www.scribd.com/doc/246326772/0521894662-Grammar-Turkish Chapter-5,  "5.1  The genitive",  PDF-page: 53  /  Book-page: 41 Chapter-5,  "5.2  Genitive-possessive structures",  PDF-page: 54  /  Book-page: 42 I think, your question is: Why is it  kar-nı  instead of  kar-ı-nı The rule's name in Turkish is: Ünlü (sesli) harf düşmesi  or shortly: Ünlü düşmesi Explanation in Turkish: http://www.tdk.gov.tr/index.php?option=com_content&view;=article&id;=179:Unlu-Dusmesi-&catid;=50:yazm-kurallar&Itemid;=132 The rule's name in English is: Dropping a vowel  or  Vowel loss  or  High vowel omission (Ooo, how many names does it have?!.. :))   I'm not shure which is the best match.) Explanation in English: http://www.turkishlanguage.co.uk/pocnoun.htm https://www.scribd.com/doc/246326772/0521894662-Grammar-Turkish Chapter-2,  "2.9  High vowel omission",  PDF-page: 29  /  Book-page: 17

Karın - tummy/belly Karnı - his/her belly Karın + ı = Karnı "ı" here is a suffix and it implies that the noun belongs to the third person in the sentence. Dudu'nun karnı - Dudu's tummy What might cause some confusion is that it's "karnı" lnstead of "karını". This is due to what we call "ünlü düşmesi". Which roughly translates to "loss of a vowel. Don't hesitate to message me if you need more information.